1 files changed, 20 insertions, 1 deletions
diff --git a/src/pkg/testing/iotest/reader.go b/src/pkg/testing/iotest/reader.go
index e4003d744..daa6ede08 100644
--- a/src/pkg/testing/iotest/reader.go
+++ b/src/pkg/testing/iotest/reader.go
@@ -58,7 +58,7 @@ func (r *dataErrReader) Read(p []byte) (n int, err os.Error) {
 			r.unread = r.data[0:n1]
 			err = err1
 		}
-		if n > 0 {
+		if n > 0 || err != nil {
 			break
 		}
 		n = copy(p, r.unread)
@@ -66,3 +66,22 @@ func (r *dataErrReader) Read(p []byte) (n int, err os.Error) {
 	}
 	return
 }
+
+var ErrTimeout = os.NewError("timeout")
+
+// TimeoutReader returns ErrTimeout on the second read
+// with no data.  Subsequent calls to read succeed.
+func TimeoutReader(r io.Reader) io.Reader { return &timeoutReader{r, 0} }
+
+type timeoutReader struct {
+	r     io.Reader
+	count int
+}
+
+func (r *timeoutReader) Read(p []byte) (int, os.Error) {
+	r.count++
+	if r.count == 2 {
+		return 0, ErrTimeout
+	}
+	return r.r.Read(p)
+}